The present invention relates to a force sensor for sensing forces, such as the draft forces applied to the implement hitch of an agricultural tractor.
To provide draft control for agricultural tractors a means of measuring the draft force is required. Known draft force measuring mechanisms for tractor draft control systems are described in U.S. Pat. No. 2,864,295, issued to Du Shane, in 1958, in U.S. Pat. No. 2,974,733, issued to Fletcher in 1961 and in U.S. Pat. No. 3,022,831, issued to Hess in 1962. In these known designs the draft force is applied to opposite ends of a bending shaft which is supported by laterally spaced apart supports. A linkage transmits the deflection of the central part of the shaft to a servo mechanism of the tractor hitch control system. However, in such designs the sensing sensitivity was limited by the stiffness and the resulting small amount of flexing of the bending shaft. Accordingly, a relatively simple, inexpensive and sensitive bending shaft type draft force sensing mechanism is desired.